Evaluating the impact of cycle helmet use...

For all discussions about this "lively" subject. All topics that are substantially about helmet usage will be moved here.
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pjclinch
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Re: Evaluating the impact of cycle helmet use...

Postby pjclinch » 15 Jul 2020, 8:51am

Jdsk wrote:A very rough cut:

Problems to be managed in studies:
the level of risk varies by cyclist behaviour that may change with helmet usage
Drivers behaviour may change by cyclists wearing helmets
Head injury is related in part to cyclist's behaviour
Helmet legislation when enforced can discourage cycling


For the first, behaviour will also change in different ways with helmets. You may have one group wearing because they're risk averse and another wearing because they embrace risk and want more of it.
Second may also vary with other factors, quite possibly related to the fist, so if A Driver comes across someone giving an air of knowing exactly what they're at (e.g. a TT rider in All The Gear) they may feel they can pass close in "safety", while a wobbly pensioner would be treated quite differently.
For the fourth, helmet promotion can discourage cycling too.

Jdsk wrote:Assertions about what is already known from studies:
wearing a helmet increases the accident rate
increases the frequency and number of helmet impacts compared to a bare head
helmet impacts generally last longer in duration than for bare head
Drivers behaviour may change by cyclists wearing helmets
Head injury is related in part to cyclist's behaviour
Helmet legislation when enforced can discourage cycling
Many differences have been reported when comparing the behaviour of injured cyclists for wearers and non-wearers.


The first of these is problematical because there's chicken <-> egg feedback in both directions: it's not a simple causal relationship. So I might take more risks because I'm wearing a helmet, but on the other I might be wearing a helmet specifically because I've chosen to take more risks (e.g., I want to do that descent trail quicker, I want to take that great corner without having to brake first, etc.).
It's also the case that risk compensation is in relation to perceived risk, so if your "increased risk" as a risk-averse type is getting on a bike at all it could be that you're actually accruing considerable health benefits by doing something you think is dangerous, but actually isn't.
And it's very much the case that different people have very different attitudes to risk and are affected differently by their perception of it, and it's difficult to account for the variation in a study aiming to see how effective helmets are. So on the last of those points, many differences in behaviour can be found in any group you select in all sorts of ways, not just whether they wear a helmet or not.

Given how hard it is to untangle the above, and how small the overall effects seem to be, I do wish people would put that sort of effort in to stuff which they know actually works...

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Re: Evaluating the impact of cycle helmet use...

Postby mikeymo » 15 Jul 2020, 9:54am

pjclinch wrote:I do wish people would put that sort of effort in to stuff which they know actually works...Pete.


To that end then, I think you teach Bikeability (or similar), yes? Do you think that works, for a middle aged bloke who already cycles, but has a deep seated phobia of death? I'm trying to think of actions I can take, personally, you see.

And especially, as we prefer studies to personal opinion and evidence free assertion, have any studies been done on the effectiveness of cycle training? Thanks.

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Re: Evaluating the impact of cycle helmet use...

Postby pjclinch » 15 Jul 2020, 10:26am

mikeymo wrote:
pjclinch wrote:I do wish people would put that sort of effort in to stuff which they know actually works...Pete.


To that end then, I think you teach Bikeability (or similar), yes? Do you think that works, for a middle aged bloke who already cycles, but has a deep seated phobia of death? I'm trying to think of actions I can take, personally, you see.

And especially, as we prefer studies to personal opinion and evidence free assertion, have any studies been done on the effectiveness of cycle training? Thanks.


Research has been done, yes, generally monitoring rather than peer review stuff I think, but part of the Bikeability initiative included keeping tabs on how it did. General indications are that the main positive outcome is greater confidence, which may be a useful thing if fear is preventing someone from getting about. That may sound like damning with faint praise, but most of my training these days is for my work (NHS Tayside) and a typical client is someone that rides a bit but finds traffic daunting. I find I can help with that.

Will it make you safer? That's not a simple question: if you end up cycling in more dangerous places with your new found confidence you may not be safer than if you weren't there. The Bikeability monitoring didn't suggest a lower accident rate after training, but a graduate is probably doing more and riskier things than someone who hadn't done the training.
Also, as above you need to look at "safer" on different fronts, so if you drive a route through town instead of riding your chances of sudden death are lower but your life expectancy and overall health through life will be lower.

Good points about training is that especially now you might find an initiative where someone else pays and you really don't have much to lose by doing it. It's not a solution for general cycle safety, but it can help you be a better cyclist.

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Re: Evaluating the impact of cycle helmet use...

Postby RickH » 15 Jul 2020, 11:09am

One of the good things about bike ability is that it teaches things that seem counter-intuitive, such as road positioning. There is still a quite well ingrained belief that you should cycle in the gutter to "keep out of the way of cars". The trouble is that encourages the cars to squeeze past in the not-really-enough-space available. In that position you are also not in the space that drivers expect to find other traffic (& cycling on the road you ARE traffic).

Anecdotally, I usually find that, on the rare occasions I get a particularly close pass, I note that for one reason or another I have drifted towards the kerb. Once I return to a riding position further out the close passes stop. I ride further out because I believe there is evidence that it is safer to do so not because I have some sort of magic protection (unless my cycle cap counts :wink:).

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Re: Evaluating the impact of cycle helmet use...

Postby reohn2 » 15 Jul 2020, 12:31pm

RickH wrote:One of the good things about bike ability is that it teaches things that seem counter-intuitive, such as road positioning. There is still a quite well ingrained belief that you should cycle in the gutter to "keep out of the way of cars". The trouble is that encourages the cars to squeeze past in the not-really-enough-space available. In that position you are also not in the space that drivers expect to find other traffic (& cycling on the road you ARE traffic).

Anecdotally, I usually find that, on the rare occasions I get a particularly close pass, I note that for one reason or another I have drifted towards the kerb. Once I return to a riding position further out the close passes stop. I ride further out because I believe there is evidence that it is safer to do so not because I have some sort of magic protection (unless my cycle cap counts :wink:).

The other thing about riding out in the road is that should you get a very close pass you then have a safety margin to the left to move into.
Whereas if you are already riding in the gutter a close pass can make you swerve left into the kerb and consequently fall,possibly back into the road as you try to counter the left fall,to possibly be hit by a following vehicle.
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Re: Evaluating the impact of cycle helmet use...

Postby mikeymo » 15 Jul 2020, 2:33pm

RickH wrote:Anecdotally, I usually find that, on the rare occasions I get a particularly close pass, I note that for one reason or another I have drifted towards the kerb.


Though the sometimes stated corollary, that motorists seem to leave more space between the motorised vehicle and the cycle, when overtaking, if that cycle is further away from the road edge, has been contradicted in one study:

"The further out into the road the experimenter cycled, the less space he received from overtaking vehicles. We therefore offer the following principle: to a first approximation, a driver follows the same path when overtaking a bicycle no matter where the bicycle is. This illustrates how the further out a rider travels, the less space will be between them and a passing vehicle on average. This finding is contrary to what many experienced bicyclists believe (including the author prior to this study). That the data so clearly proved this belief wrong is, as well as anything else, an excellent illustration of the need for objective research over subjective experience when seeking to understand traffic behaviour." [my emphasis]

https://www.sciencedirect.com/science/article/pii/S0001457506001540

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Re: Evaluating the impact of cycle helmet use...

Postby RickH » 15 Jul 2020, 9:56pm

mikeymo wrote:
RickH wrote:Anecdotally, I usually find that, on the rare occasions I get a particularly close pass, I note that for one reason or another I have drifted towards the kerb.


Though the sometimes stated corollary, that motorists seem to leave more space between the motorised vehicle and the cycle, when overtaking, if that cycle is further away from the road edge, has been contradicted in one study:

"The further out into the road the experimenter cycled, the less space he received from overtaking vehicles. We therefore offer the following principle: to a first approximation, a driver follows the same path when overtaking a bicycle no matter where the bicycle is. This illustrates how the further out a rider travels, the less space will be between them and a passing vehicle on average. This finding is contrary to what many experienced bicyclists believe (including the author prior to this study). That the data so clearly proved this belief wrong is, as well as anything else, an excellent illustration of the need for objective research over subjective experience when seeking to understand traffic behaviour." [my emphasis]

https://www.sciencedirect.com/science/article/pii/S0001457506001540

On the sort of roads I'm travelling on it usually means they can't overtake without crossing the white line if I'm further out. It also means that they can't overtake without pulling out to some extent. I find the vast majority then leave a reasonable space when they do pass (although not always choosing a big enough gap to not cause oncoming cars to have to take evasive action :roll:). The passes can still be maybe a bit closer than ideal but not enough to bother me unduly. On wider roads, where it is hard to "block" a car, it may well be different. But I don't often ride those sort of roads.

I did say anecdotally - that it is my general experience in the area that I cycle.

I've not read the report as I don't have access to it. (I must get round to sorting that out as I'm probably able to do so through my old Uni.)

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Re: Evaluating the impact of cycle helmet use...

Postby pjclinch » 16 Jul 2020, 8:39am

Most typically cycling according to the National Standards for Cycle Training is seen as using 2 positions, Primary and Secondary. Secondary is a whole can of worms as to where it effectively is (I was involved in a consultation over teaching positioning earlier this year, it's not just a case of cut and paste from Cyclecraft) but Primary is generally reasonably easy to pin down as the middle of your lane.

A lot of the point of Primary is to control the traffic behind you to quite specifically discourage overtaking, but we all know the MGIF brigade will often have other ideas about that and come past anyway. And when they do, because you're quite deliberately created an outsized gap from the kerb, the overtake will be closer than if you're in Secondary.

My (unmeasured, anecdotal) experience is that there are some reasonably wide roads where Primary just doesn't work that well because there's still perceived to be squeeze room past you when you're in it. I suspect it's not simply a factor of how far from the kerb you are but how much room there is on the other side too. Probably other variables too.

(The Cycling Scotland position teaching looks to be heading for a Secondary that's taught as at least a metre, rather than Cyclecraft's 50cm)
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Re: Evaluating the impact of cycle helmet use...

Postby Vorpal » 16 Jul 2020, 8:57am

I would add to that....

Primary position can be effectively used to control traffic. That only works if the driver behind (or in some cases on-coming) cannot reasonably get around the cyclist without going into the next lane, so for a junction, pinch point, blind bend, etc.

IMO, primary position may result in closer passes when it is used needlessly (i.e. there is no reason to control traffic), or as pjclinch says, the road is wider.

Also, there are some rural lanes that are of an unfortunate width where they are technically single track, but in practice almost two lanes wide (two cars can pass each other slowly & with care), but too wide for primary position to be useful. So, most drivers will percieve that there is enough space to overtake/pass a cyclist (possibly without slowing) whether the cyclist is in primary or secondary. I used to use one fairly regularly, and experimented with road position there, and anecdotally secondary produced better overtakes than primary. Other places, like one road narrowed by parking, primary was clearly better.

The results of Walker's experiment weren't especially remarkable from the persepctive of road position. I think that he drew that correct conclusions from it that cyclist appearance and behaviour may affect how drivers overtake, but I don't think that from that experiment we can make any conclusions about the general effect of primary position on driver behaviour.
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Re: Evaluating the impact of cycle helmet use...

Postby PaulaT » 16 Jul 2020, 10:45am

RickH wrote:On the sort of roads I'm travelling on it usually means they can't overtake without crossing the white line if I'm further out. It also means that they can't overtake without pulling out to some extent. I find the vast majority then leave a reasonable space when they do pass (although not always choosing a big enough gap to not cause oncoming cars to have to take evasive action :roll:). The passes can still be maybe a bit closer than ideal but not enough to bother me unduly. On wider roads, where it is hard to "block" a car, it may well be different. But I don't often ride those sort of roads.

I did say anecdotally - that it is my general experience in the area that I cycle.


That's very much my experience too. Riding out from the kerb a bit also means you're clear of roadside drains so don't need to suddenly pull out to miss one (risky if there's a vehicle close behind).

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Re: Evaluating the impact of cycle helmet use...

Postby Jdsk » 16 Jul 2020, 10:49am

Vorpal wrote:The results of Walker's experiment weren't especially remarkable from the persepctive of road position. I think that he drew that correct conclusions from it that cyclist appearance and behaviour may affect how drivers overtake, but I don't think that from that experiment we can make any conclusions about the general effect of primary position on driver behaviour.

But it did show that experiments are possible. We need a lot more. And the technology has become so much easier and cheaper.

Jonathan

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Re: Evaluating the impact of cycle helmet use...

Postby mikeymo » 16 Jul 2020, 11:04am

Jdsk wrote:
Vorpal wrote:The results of Walker's experiment weren't especially remarkable from the persepctive of road position. I think that he drew that correct conclusions from it that cyclist appearance and behaviour may affect how drivers overtake, but I don't think that from that experiment we can make any conclusions about the general effect of primary position on driver behaviour.

But it did show that experiments are possible. We need a lot more. And the technology has become so much easier and cheaper.

Jonathan


When I first heard of Ian Walker's experiment, I thought it significant. I've read the re-analysis of his data. I've read the commentary pointing out his at best, misleading, and at worst, dishonest, use of pictorial graphs (y-axis that don't start at 0). I've read his home page and his list of concerns, which make his bias clear. I've considered the fact that the researcher, author and primary subject were all the same person in the study.

In answering my question - "shall I put a cycle helmet on when I go out on my bike today?" - I think Ian Walker's study is ignorable. Until a lot more studies are done, and more stringent ones at that, I will continue to ignore it.

Mind you, I might still buy a wig to wear. It'll be useful for some of the parties I get invited to.

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Re: Evaluating the impact of cycle helmet use...

Postby Steady rider » 16 Jul 2020, 8:09pm

Evidence of proposed UK law regarding motorists passing cyclists, Cycling Colloquium in Aveiro, Portugal, 18 November 2016.
https://www.researchgate.net/publicatio ... g_cyclists

Cycling UK advised members not to support an AGM motion seeking a passing law.

https://www.cyclinguk.org/sites/default ... _final.pdf
Cycling UK poor reply prevented Motion No2 going forward. Last year at least one conference to discuss issues.
https://hackney.gov.uk/london-walking-c ... conference

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Re: Evaluating the impact of cycle helmet use...

Postby Nigel » 16 Jul 2020, 10:44pm

pjclinch wrote:Most typically cycling according to the National Standards for Cycle Training is seen as using 2 positions, Primary and Secondary. Secondary is a whole can of worms as to where it effectively is (I was involved in a consultation over teaching positioning earlier this year, it's not just a case of cut and paste from Cyclecraft) but Primary is generally reasonably easy to pin down as the middle of your lane.


Another factor is road surface.
On the rural and quiet roads of S.Scotland, the surface is the big "downer". On roads which are not falling apart, there are often two smoother lines worn by the road vehicles, and a rougher bit between, which is tiring to ride on due to the vibrations. So, my usual position is in one of the smoother lines.
Some roads are falling apart, with potholes and broken surfaces, so lines there are "whatever looks not too rough". The very worst will have lost all their top surface, and one picks a cautious line through the rubble foundations.


(The Cycling Scotland position teaching looks to be heading for a Secondary that's taught as at least a metre, rather than Cyclecraft's 50cm)


Seems very sensible. Particularly as the 50cm might suddenly disappear in an edge collapse or a dropped drain.


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